Enhancing the mechanical properties and corrosion resistance of biomedical Ti15Mo alloy with ultra-finer {332} twins via cyclic deformation

Mechanical properties, passivation behaviors and corrosion resistance of biomedical Ti15Mo alloy with ultra-finer twins were investigated. Cyclic deformation was conducted to activating more {332} twin variants via periodic changes of tension and compression. Microstructural refinement via numerous twins with the stable boundaries is different from other mechanisms, resulting in a higher hardness and maintaining the low elastic modulus after deformation and annealing. The results of electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy tests, revealed that twin boundaries are beneficial to enhancing passivation behaviors via forming a thicker oxide film in PBS solution. The alloy with ultra-finer {332} twins exhibit a better corrosion resistance due to a lower passivation current. The expected biomedical performance was obtained in the alloy after ±3 % amplitude cyclic deformation and 730 °C/7 min annealing, in contrast to the initial alloy with coarse grains, increasing 8.8 % of the hardness, decreasing 46 % of the corrosion current and maintaining the low elastic modulus.